This paper presents recent improvements of our new solar concentrator design for space application. The concentrator is based on a combination of a diffraction grating (blazed or lamellar) coupled with a Fresnel lens. Thanks to this diffractive/refractive combination, this optical element splits spatially and spectrally the light and focus approximately respectively visible light and IR light onto electrically independent specific cells. It avoid the use of MJs cells and then also their limitations like current matching and lattice matching conditions, leading theoretically to a more tolerant system. The concept is reminded, with recent optimizations, ideal and more realistic results, andmore » the description of an experimental realization highlighting the feasibility of the concept and the closeness of theoretical and experimental results.« less

This paper reports work on pentenary alloy systems similar to the quarternary system in In/sub 1-x/Ga/sub x/P/sub 1-y/As/sub y/. Such A/sup I//sub 1-y/B/sup I//sub y/C/sup III/D/sup VI//sub 2x/E/sup VI//sub( 21-x/) and A/sup II//sub 1-y/B/sup II//sub y/C/sup IV/D/sup V//sub 2x/E/sup V//sub( 21-x/) pentenary alloys are mixtures of ternary chalcopyrites of the I-III-VI/sub 2/ and II-IV-V/sub 2/ variety. These materials are of interest because their use can improve the performance of heterojunction electro-optic devices such as solar cells. This improvement arises because the pentenaries can permit different semiconductor layers to be deposited upon each other such that they are lattice and crystallographicallymore » matched, but at the same time have independently adjustable band gaps. More specifically, we have focused on the Cu/sub 1-y/Ag/sub y/InS/sub( 21-x/)Se/sub 2x/ system which appears to have the best potential of all the possible systems for solar energy applications. Samples were prepared by reacting stoichiometric powder mixtures at about 900 /sup 0/C. X-ray diffractometry indicated complete solid solubility over the whole compositional range. Cathodoluminescence was used to determine band gaps at 300 and 77 /sup 0/K and the spectra indicate that all alloys are direct-band-gap semiconductors. Isolattice constant and band-gap contour maps for the system have been obtained.« less